253-hwk-25a - HPHY 253 Homework 25a The Electric Potential...

HPHY 253 Homework 25a The Electric Potential Dr. A. E. Bak Name 25 : 5 . An electron moving along the x axis has an initial speed of 3 : 70 10 6 m=s at the origin. Its speed is reduced to 1 : 40 10 5 m=s at the point x = +2 : 00 cm . Calculate the potential di/erence between the origin and that point. Which location is at the higher potential? 25 : 7 . A block having mass m and charge + Q is connected to an insulating spring having force constant k . The block lies on a frictionless, insulating horizontal track, and the system is immersed in a uniform electric ±eld of magnitude E directed as shown in Figure P 25 : 7 . The block is released from rest at a moment when the spring is unstretched (that is, when x = 0 ). (a) By what maximum amount does the spring expand? (b) What is the equilibrium position of the block? (c) Show that the block²s motion is simple harmonic and determine its period. (d)

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